10 Top-Selling Drugs Coming Off Patent

Ten of the world's top-selling prescription drugs are about to get cheaper.

Over the next 17 months, the patents on brand-name medications like the cholesterol-lowering drug Lipitor and the blood thinner Plavix will expire, opening the door for generic versions that could cost up to 80 percent less. Name brand drug costs could also fall because of the new competition. It might be bad news for drug makers, but good news for patients.

Here's a look at the 10 blockbuster drugs coming off patent.

Blockbuster Drugs Coming Off Patent

Plavix

When a clot builds up or lodges in a blood vessel, it restricts blood flow and could cause a heart attack or stroke. Plavix, which belongs to a class of drugs called blood-thinners or anti-platelets, can help keep blood flowing smoothly -- for about $162 per month. In 2010, Plavix earned co-marketers Bristol-Myers Squibb and Sanofi-Aventis more than $6.1 billion in U.S. sales. A generic version could be available in the U.S. in May 2012.

Blockbuster Drugs Coming Off Patent

Lipitor

High blood levels of cholesterol can lead to a build-up of fat on the inside of blood vessels, narrowing the opening through which the blood can flow and increasing the risk of heart attack and stroke. Lipitor, which belongs to a class of drugs called statins, can decrease the amount of cholesterol in the blood and lower heart attack and stroke risk. It can cost up to $168 per month. In 2010, Lipitor earned Pfizer more than $5.3 billion in U.S. sales. A generic version could be available in the U.S. in November 2011.

Blockbuster Drugs Coming Off Patent

Seroquel

Seroquel is used to treat the symptoms of schizophrenia and bipolar disorder. It belongs to a class of drugs called atypical antipsychotics, which work by changing the activity of certain chemicals in the brain. Depending on the dose, the drug costs about $549 per month. In 2010, Seroquel earned AstraZeneca more than $3.7 billion in U.S. sales. A generic version could be available in the U.S. in the spring of 2012.

Blockbuster Drugs Coming Off-Patent

Actos

Actos is used to treat type 2 diabetes -- a chronic disease that's on the rise nationwide. The drug belongs to a class of medications called thiazolidinediones and can increase the body's sensitivity to insulin and help control blood sugar levels. It costs up to $241 per month. In 2010, Actos earned Japanese manufacturer Takeda more than $3.3 billion in U.S. sales. A generic version could be available in the U.S. in August 2012.

Blockbuster Drugs Coming Off-Patent

Enbrel

Enbrel is used to treat the autoimmune diseases rheumatoid arthritis and psoriasis. The drug, which belongs to a class of medications called tumor necrosis factor (TNF)-alpha inhibitors, acts as a decoy receptor in the body and soaks chemicals that propagate the autoimmune reaction. It costs up to $2,784 per month. In 2010, Enbrel earned Amgen more than $3.3 billion in U.S. sales. The patent expires in August 2012. But because the drug is a "biologic" that mimics the body's own receptor, it's subject to different laws and companies can't manufacture a generic version in the U.S.

Blockbuster Drugs Coming Off-Patent

Levaquin

Levaquin is an injectable antibiotic used to treat pneumonia as well as infections of the sinus, urinary tract, kidney and skin. A generic version of the drug, which belongs to a class of bacteria-killing medications called fluoroquinolones, is available in tablet form. But the injectable form is still under patent. In 2010, Levaquin earned over Johnson & Johnson $1.3 billion in U.S. sales.

Blockbuster Drugs Coming Off-Patent

Zyprexa

Zyprexa, like Seroquel, is an atypical antipsychotic used to treat the symptoms of schizophrenia and bipolar disorder. It costs up to $641 per month. In 2010, Zyprexa earned Eli Lilly almost $3.5 billion in U.S. sales. A generic version could be available in the U.S. in October 2011.

Blockbuster Drugs Coming Off-Patent

Concerta

Concerta is used to control symptoms of attention deficit hyperactivity disorder (ADHD) -- a condition marked by difficulty focusing and remaining still or quiet that affects adults and children. It's also used to treat narcolepsy. The drug, which belongs to a class of medications called central nervous system stimulants, works by changing the concentrations of certain chemicals in the brain. It costs up to $236 per month. In 2010, Concerta earned Johnson & Johnson $929 million in U.S. sales. A generic version could be available in the U.S. in 2011.

Blockbuster Drugs Coming Off-Patent

Protonix

Protonix is used to treat gastroesophageal reflux disease and conditions that cause the stomach to produce too much acid. The drug, which belongs to a class of medications called proton-pump inhibitors, works by decreasing the amount of acid made in the stomach. It costs up to $173 per month. In 2010, Protonix earned Pfizer $690 million in U.S. sales. A generic version could be available in the U.S. in 2011.